Modern hemodialysis technology enables patients with chronic renal failure to live independently between dialysis treatments. Patients utilize this technology as a means of filtering the toxins from their blood by passing blood out of their body through a hemodialysis machine. The hemodialysis machine removes blood toxins by exposing the blood to dialyzing fluid across a semipermeable membrane, in effect creating an artificial kidney.
In order to properly process a patient's blood a graft is made, preferably in patient's arm. At the site of the graft a shunt is placed to connect an artery having a high rate of blood flow with a vein. The shunt provides a convenient inlet on the artery side for blood requiring dialysis filtration processing; the outlet is located on the vein side for return of dialysis processed blood from the hemodialysis station.
The dialysis shunt, while providing a convenient arrangement for hemodialysis processing, may become inoperable after a period of time due to stenosis caused by the high rate of blood flow through the shunt and repetitive injury at the venous anastomosis. Typically, patients must have these constricting portions of the shunt widened periodically in order to continue hemodialysis processing through the shunt.
Shunt blockage is generally treated through a combination of surgical devices and/or pharmaceutical treatments; these techniques are often cost prohibitive and/or require an incision. For example, pharmaceutical treatments generally employ urokinase which, depending on the amount used, can cost upward of $350.00 per application and possibly cause bleeding complications.
Mechanical thrombolysis apparatus and methods for performing thrombolysis are known, being disclosed in U.S. Pat. No. 4,646,736 to Auth, U.S. Pat. No. 5,078,722 to Stevens and U.S. Pat. No. 5,695,507 to Auth, et al.
The apparatus disclosed in these patents seeks to penetrate thrombolytic structures by introducing, for example in the case of '507, a rotating core wire into the thrombus, seeking to withdraw fibrin from the thrombus into the rotating core wire thereby breaking up the network of the thrombus which is preventing blood flow.